Chinese courier ZTO Express and the underwriters of its New York stock market listing have been sued by a U.S. pension fund that alleges the firm exaggerated its profit margins to lure investors into its US$1.4 billion initial public offering (IPO).

Morgan Stanley and Goldman Sachs Group Inc., which spearheaded ZTO’s IPO, are named in the class-action suit filed in Alabama state court by the city of Birmingham’s pension fund which says that they failed to do adequate due diligence.

ZTO’s listing was the largest U.S. listing in 2016 and was the biggest by a Chinese company since the US$25 billion IPO of e-commerce giant Alibaba Group Holding Ltd. in 2014.